The invention relates to metal recuperators, especially those used to recapture heating energy from hot exhaust gas which is normally vented into the atmosphere through a flue pipe or stack. Such recuperators are normally made of stainless steel components which are of welded construction, thereby making the dismantling and replacement of the entire recuperator, upon wear, very time consuming and costly, especially when the downtime of the furnace or oven to replace the recuperator, is considered. The invention is directed to solving this problem by the provision of a simplified, unwelded recuperator structure wherein the parts, subject to higher temperatures and greater wear, are easily removed and replaced with a minimum of downtime necessitated to make the repairs since no welds need be broken, as is the case when recuperators of welded construction, are replaced.
Briefly stated, the invention is in a recuperator which comprises an outer, hollow casing which is fixedly mounted on, for example, an elbow of a flue pipe or stack. The casing is provided with an inlet through which fluid enters the casing and an outlet through which the fluid exits the casing. A hollow housing is removably mounted interiorly of the casing and forms with the casing an outer fluid passageway which extends between the fluid inlet and outlet. An inner fluid passageway is formed within the housing and extends longitudinally of the casing. The inner fluid passageway is also provided with an inlet port and an outlet port through which another fluid, at a different temperature, is circulated through the inner fluid passageway into heat exchange relation with fluid being circulated through the outer fluid passageway in an opposite direction. Special seals are provided at each end of the casing between the housing and casing and elbow to seal the fluid passageways from each other and the ambient atmosphere, while allowing expansion and contraction of the housing relative to the casing.
Another aspect of the invention is the provision of a core, which is placed within the housing to channel the fluid passing through the housing into greater heat exchanging relation with fluid circulating through the outer fluid passageway.